'use strict';

function get_union(collection_a, collection_b) {
  //在这里写入代码
  var s = [];

  for (let i = 0; i < collection_b.length; i++) {
    if (!collection_a.includes(collection_b[i])) {
      s.push(collection_b[i]);
    }
  }
  var result=collection_a.concat(s);
  return result;
}
module.exports = get_union;
